This invention relates generally to a sliding sash window incorporating a frictional positioner shoe which is adapted to slide within a channel of a jamb liner mounted to a window jamb, while applying suitable friction to hold the sash in place at any selected raised position. More particularly, the invention relates to a frictional positioner shoe for a sliding, pivotable sash which includes a rotatable member connected to the sash to be rotated thereby and which moves axially when so rotated, in order to move a brake surface into engagement with a wall on the jamb liner and thus inhibit or retard vertical and rotational movement of the sash when it is tilted out of the plane of the window opening.
Several types of pivot shoe assemblies are known for pivotally mounting a window sash in its opening and for supporting the window sash at a desired height when the sash is tilted away from the plane of the window opening. Such known pivot shoe assemblies generally provide braking action only when the window sash is tilted out of the plane of the window and away from the jambs, and these do not provide any significant resistance or braking action against vertical movement of the window sash as it tracks along the jamb liners mounted to the jambs. Although such windows do generally incorporate a balance device such as a tension spring which counters the weight of the window sash to minimize the amount of force needed to raise and lower the window sash, such balance devices are not intended to, and do not usually restrain the window sash against vertical movement within the jambs. Typically, some additional positioning member is used for this purpose, for example a friction mechanism of some type, since few windows are so perfectly balanced (for example, one wherein the weight of the window sash is precisely countered by the tension of a balance tension spring) that they merely remain in their various different positions by themselves, or merely by whatever frictional contact exists between the jamb liner and the sash. Reliance on frictional contact between the jamb liner and sash to hold the sash in place once it has been raised can often lead to undesirable results wherein it becomes necessary to prop the sash up to keep the window open. Accordingly, a frictional positioning shoe which serves the dual function of providing increased restraint against rotational movement of the sash when it is tilted open such as for cleaning the outside of the windowpane, while also providing frictional resistance against vertical movement when the window sash is vertically raised within the plane of the window opening, is very desirable.
Another disadvantage with several of the known pivot shoe assemblies is that they are often comprised of many components, such as three or more components including a member which slides within a channel in a jamb liner, a rotatable barrel cam positioned within an opening in the slidable member, and a brake shoe which moves axially when the barrel cam is rotated. The complexity, number of manufacturing and assembly steps required during production, and hence the ultimate cost, of an article, such as a sliding, pivotable sash type window, generally increases when more components are used. It is therefore desirable to provide a frictional positioner shoe which facilitates pivotal mounting of a window sash and provides resistance against vertical and rotational movement of the sash when it is tilted away from the jambs, and which has fewer components to simplify manufacturing and assembly of sliding, pivotable sash type windows.
Many of the known pivot shoe assemblies include elements which are deformed or which cause deformation of the jamb liner when the window sash is pivoted. Deformation of the jamb liner, which is usually made of a material having a relatively low resilience such as rigid polyvinyl chloride, is particularly undesirable and can eventually lead to damage thereof. While the components of the pivot shoe have generally been made of a relatively stiffly resilient material such as nylon, repeated use and deformation of such a pivot shoe can eventually adversely affect the operating characteristic thereof. Accordingly, it would be even more desirable to provide a frictional positioner shoe for slidable, tiltable sash type windows which would provide restraint or braking action against vertical and rotational movement of the sash as it is swung away from the plane of the window opening, substantially without any significant distortion, deformation or damage to the positioner shoe or to the jamb liner.